The objective of the Toxicology Training Program at the University of Rochester School of Medicine is to provide quality pre- and postdoctoral training in toxicology. The Program is housed within the Department of Environmental Medicine, but its focus is multidisciplinary and interdisciplinary. One-third of the faculty (17 out of 50) have their primary appointments in the Department of Environmental Medicine, and the rest of the faculty come from a total of 16 different departments within the School of Medicine and Dentistry. As such, this Training Program takes advantage of the great diversity of specialties and resources available at a major academic Medical Center by reaching beyond the immediate confines of a single basic science group to draw in faculty research programs span the entire spectrum of toxicology, from molecular mechanisms to cellular processes to whole animals and human populations. There are seven major training areas: Neurotoxicology, Pulmonary Toxicology, Osteotoxicology, Molecular Modifiers of Toxicity, Carcinogenesis, Immunotoxicology, and Reproductive and Developmental Toxicology. This Training Program is distinguished by a long history of outstanding research and training in toxicology, the many accomplishments of its former and current students, fellows, and faculty, the remarkable collegiality and extensive research collaborations among its faculty members and trainees, an extensive base of research support, and by a strong institutional commitment to research and training in the environmental health sciences. The Program is further enhanced by the presence of an NIEHS Environmental Health Sciences Center, an EPA Center, and a Division of Occupational Medicine within the Department of Environmental Medicine, and an integrated Biomedical Sciences Graduate structure at the School of Medicine and Dentistry. There are presently 28 Toxicology Ph.D. students in residence, with 12 new Toxicology Ph.D. trainees starting in August 2002, and 23 postdoctoral fellows currently in training. The present application requests an additional five years of funding for 18 predoctoral and 3 postdoctoral trainees per year.